A changing arm is generally constructed two-armed. During the changing operation, one arm grips the side of the tool and removes the tool from the spindle while the other arm simultaneously removes the new tool from the tool store. The changing arm thereafter swings so that the new tool is placed in front of the spindle and the used tool placed in front of the store. By moving the changing arm in direction of the spindle axis, the new tool is inserted into the spindle and the used tool inserted in the tool store. The changing arm then releases the inserted tool, however, remains in a position which is in front of the spindle so that the next tool change can take place without delay.
The advantage of the described arrangement with a tool-changing device which can be moved with the spindlehead is that the tool changing operation can take place directly after each operation without requiring the spindlehead to be brought into a changing position which lies opposite the stationary store.
An important disadvantage of this arrangement is, however, that the tool-changing device, in particular the changing arm remains in front of the spindle after the changing operation and prevents receiving a multiple-spindle unit which is driven by the spindle, so that spindleheads having a tool-changing device of the described kind could not up to now be constructed to receive multiple-spindle units and thus strongly limit the universality of the entire machine.
The purpose of the present invention is to improve a spindlehead having a tool-changing device in such a manner that it can be used universally and that in particular multiple-spindle units can be used.
This purpose is inventively attained by the spindle-head being adapted to accommodate a multiple-spindle unit which can be driven by the spindle, whereby said multiple-spindle unit has a recess into which recess the changing arm projects when the multiple-spindle unit is mounted on the spindlehead.
The changing arm, which is not used to accommodate the spindlehead to the multiple-spindle unit, may maintain its position in front of the spindle. Through this, it is possible to include the multiple-spindle unit just as would be various individual tools into the work sequence.
The multiple-spindle unit is added to the spindlehead and is driven centrally by the tool spindle. For this purpose, it is provided according to one characteristic of the invention that for driving the multiple-spindle unit there is provided a driving sleeve which can be inserted by the changing arm into the spindle, whereby a recess in the multiple-spindle unit has a corresponding size which offers space for the driving sleeve and the changing arm.
The change from a conventional tool to the multiple-spindle unit occurs then as follows:
The tool is removed from the spindle by the changing arm and is replaced by the driving sleeve which is stored in the tool store, which driving sleeve is just like the tools chucked in the spindle. The multiple-spindle unit is then added to the spindlehead, whereby the possibility exists that the spindlehead receives automatically the multiple-spindle unit from a storage place.
The multiple-spindle unit is secured on the spindle-head according to the characteristic of the invention by several locking rods which can be extended in direction of the spindle axis and can be locked in the multiple-spindle unit.